The present invention refers to a milking robot for handling teatcups of a milking machine and cleaning cups for cleaning the teats of an animal prior to milking. The milking robot is especially configured for attaching the cleaning cup and/or the teatcups to the teats of the animal. More precisely, the invention refers to a milking robot according to the pre-characterizing part of claim 1. The invention also refers to a milking arrangement.
It is known to use industrial robots within the manufacturing industry. It is also known to use an industrial robot as a so called milking robot in connection with milking of animals, see for instance EP-A-900 522.
An industrial robot is, according to the European Standard EN ISO 10218-1:2008, an automatically controlled, reprogrammable multipurpose manipulator, programmable in three or more axes, which may be either fixed in place or mobile for use in industrial automation applications.
One known problem of industrial robots is the phenomenon of singularities. There are several causes to singularities. Workspace interior singularities are those which occur inside but away from the workspace boundary and generally are caused by two or more joint axes lining up, see Introduction to ROBOTICS; mechanics and control; second edition; John J. Craig, 1995; page 173. A singularity occurs in a joint of a multi-link robot when the acceleration of one link would be infinite. In other words, a singularity means that the robot can choose between two or more different link positions to reach an arbitrary position in the three-dimensional workspace. If a singularity occurs, the industrial robot can run out of control, and is thus not safe.
The milking robot disclosed in EP-A-900 522 comprises a first link rotatable around a first vertical axis to a first angle within a first angle range via a first joint, a second link attached to the first link and rotatable around a second axis to a second angle within a second angle range via a second joint, and a third link attached to the second link and rotatable around a third axis to a third angle within a first angle range via third joint. A gripper is attached to the third link.
The gripper of EP-A-900 522 is rotatable around a first turning axis being parallel to the third link and around a second turning axis being perpendicular to the first turning axis in order to enable the gripper to hold the teatcup in a vertical position or in an inclined position corresponding to a possible inclination of the teat. However, due to the gripper being rotatable around the second turning axis a singularity does occur. For a given inclination or position of the gripper, with respect to the second turning axis, several values of the first, second and third angles are possible. Consequently, the design shown in EP-A-900 522 can not be regarded as sufficiently safe in all possible situations that can occur in a milking stall and during a milking operation.